Fate and transport of per- and polyfluoroalkyl substances (PFAS) in wastewater treatment plant (WWTP) effluent discharged to rapid infiltration basins (RIBs) is investigated using data from 26 WWTPs in Michigan, USA. PFAS were found to accumulate in groundwater downgradient from RIBs with median groundwater-effluent enrichment factors for ten commonly detected, terminal-form perfluoroalkyl acids (PFAAs) ranging from 1.3 to 5.2. Maximum contaminant levels for drinking water were exceeded in groundwater at all WWTPs with available PFAS data. Numerical models of unsaturated fluid flow and PFAS transport honoring RIB site properties, such as median vertical separation distance to the water table and a realistic range of area-normalized effluent fluxes, show long-chain PFAS undergo significant delays from air-water interface (AWI) adsorption, requiring up to 15 times longer to reach maximum mass flux to the saturated zone under low-flux conditions, where AWI area is 2.5 times greater. Short-chain PFAS commonly detected in effluent are only minimally affected by AWI adsorption and show little to no attenuation under high-flux conditions. The nonlinear inverse relationship between water content and AWI area highlights the important role of AWI adsorption in modulating unsaturated transport of long-chain PFAS to underlying groundwater due to the broad range of flux rates applied to RIB systems.

中文翻译：

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废水处理厂排放到快速渗透池的污水中 PFAS 的环境归宿和运输


使用来自美国密歇根州 26 个 WWTP 的数据，研究了排放到快速渗透池 （RIB） 的废水处理厂 （WWTP） 污水中全氟烷基和多氟烷基物质 （PFAS） 的归宿和运输。发现 PFAS 在 RIB 的地下水中下梯度中积累，其中 10 种常见检测到的末端全氟烷基酸 （PFAA） 的地下水富集因子中位数为 1.3 至 5.2。根据可用的 PFAS 数据，所有污水处理厂的地下水中饮用水污染物含量均超过最高水平。不饱和流体流动和 PFAS 传输的数值模型遵循 RIB 场地特性，例如到地下水位的中位垂直分离距离和实际面积归一化流出通量的范围，表明长链 PFAS 在气-水界面 （AWI） 吸附中经历了显著的延迟，在低通量条件下，需要长达 15 倍的时间才能达到饱和区的最大质量通量， 其中 AWI 面积大 2.5 倍。在污水中通常检测到的短链 PFAS 受 AWI 吸附的影响很小，并且在高通量条件下几乎没有衰减。含水量和 AWI 面积之间的非线性反比关系突出了 AWI 吸附在调节长链 PFAS 向底层地下水的非饱和传输中的重要作用，因为 RIB 系统应用的通量范围很广。